CN109479358B - Multi-lamp luminaire and method of operating the same - Google Patents

Abstract

A method of operating a group of lamps in a multi-lamp luminaire, each lamp being operable to emit a respective illumination embedded with a predetermined coded light message, and each lamp comprising a respective local controller; wherein the method comprises the following steps: communicating between local controllers of lamps within a multi-lamp luminaire for coordination such that out-of-sync instances of the encoded light message are not transmitted from different ones of the lamps in the multi-lamp luminaire.

Description

Multi-lamp luminaire and method of operating the same

Technical Field

The present disclosure relates to lamps for use between one or more other lamps in a multi-lamp luminaire (multi-lamp lighting), wherein the lamps are operable to emit coded light. For example, these lamps may be retrofit (retrofittable) LED-based replacements for conventional fluorescent tubes or incandescent bulbs.

Background

A luminaire (luminaire) is a device comprising at least one lamp for emitting illumination (illumination) and any associated socket, support and/or housing. The luminaire may take any of a variety of forms, such as a conventional ceiling or wall mounted luminaire, a floor standing luminaire or wall light or a less conventional form such as an illumination source built into a surface or furniture or any other type of lighting device for emitting illumination into the environment. A lamp refers to an individual light emitting component within a luminaire, where each luminaire may have one or more light emitting components. The lamp may also take any of a number of forms, such as an LED-based lamp, a gas discharge lamp, or an incandescent bulb. An increasingly popular form of lamp is a retrofit LED-based lamp that includes one or more LEDs as a means for emitting illumination, but which is made retrofittable as a luminaire designed for a conventional incandescent bulb or fluorescent tube.

The luminaire or even individual lamps may also be equipped with a wireless communication interface, allowing the luminaire or lamp to be controlled remotely with lighting control commands received from a user device such as a smartphone, tablet computer, laptop or desktop computer, or wireless wall switch, and/or based on sensor readings received from one or more remote sensors. Today, the communication interface can be directly included within the lamp itself (e.g., in an end-cap for retrofit replacement of an incandescent bulb or fluorescent tube). This can allow a user to turn on and off the illumination of the lights through the user device, dim up or down (dim) illumination levels, change the color of the emitted illumination, and/or create dynamic (time-varying) lighting effects, for example. In one form, the communication interface is configured to receive lighting control commands and/or shared sensor data via a local, short-range radio access technology such as Wi-Fi, 802.15.4, ZigBee or Bluetooth. Such a lamp may sometimes be referred to as a "connected" lamp.

It is further known that: illumination devices using LEDs may be used to convey information. US patent application US2015/0102733a1, for example, discloses a light (source) comprising an LED, wherein the LED produces light and can be turned off briefly, for example periodically for a duration imperceptible to the human eye, so that the light receives a command optically. For example, using a removal control device, optically emitted commands can be sent to the light. The illumination device can receive data using the currently off LED and then configure the light accordingly.

One type of connected lamp is a quick-fit "tube LED" (TLED) lamp, which is retrofit into a luminaire designed for a conventional fluorescent tube. According to the fast-match TLED scheme, the existing fixed-output fluorescent ballast, TLED lamp socket, and all electrical wiring within the luminaire remain unchanged. Via straightforward re-lighting (re-lighting), existing "dumb" fluorescent tubes (or even "dumb" TLED tubes) can be exchanged with dimmable connections TLEDs, each with an individual integrated radio station.

In other "smart" or "connected" lighting applications, the ability to embed data into the illumination emitted by a luminaire by modulating properties such as the intensity of the emitted light in order to encode the data (preferably at a frequency sufficiently high beyond human perception or at least tolerable to humans). This is sometimes referred to as "coded light" (CL) or "visible light communication" (VLC).

For example, each luminaire may be arranged to issue a different respective ID code (at least unique within the system in question, e.g. within a given building) that is unique to the respective luminaire. The look-up table may also be made available to mobile user terminals, e.g. hosted on a server and made available via a local wireless network and/or the internet or stored locally on the user terminal. The look-up table maps at least one respective information block to each of the IDs, e.g. the location of the respective luminaire. By using a light sensor (e.g., a camera) built into the user terminal, an application running on the user terminal can detect an ID embedded in light currently encountered on the user's present location (e.g., the user points the camera up to a particular luminaire). The application then accesses a lookup table to look up the information mapped to the ID. For example, if this information includes the location of the respective luminaires, this can be taken as an approximate location of the user terminal (and hence the user). In a more complex variant, light from multiple nearby luminaires and respective embedded IDs can be used by an application to compute a more accurate location fix using measurements of the received coded light signal (e.g., received signal strength, time of flight, and/or angle of arrival) and suitable positioning algorithms (e.g., triangulation, trilateration, multilateration, and/or fingerprinting techniques).

Such techniques have particular application to indoor positioning where satellite-based positioning systems (e.g., GPS, Galileo or GLONASS) cannot penetrate. However, nothing prevents such positioning techniques from being used outdoors as well. Either way, these positioning (i.e. localization) techniques can be used for many purposes, such as navigation, i.e. displaying to the user's current location on a map on his/her terminal to help him/her find his/her way; or to provide location-dependent services, e.g. the user is only allowed to perform certain actions, such as controlling lighting or heating or making location-dependent payments if detected to be within a certain predefined area.

Alternatively, in still further applications, other information may be mapped to the ID, such as location-based infotainment or advertising. Or, as yet another possibility, the information of interest can be directly (explicitly) embedded in the light without the need for a lookup.

Disclosure of Invention

Now consider the case where a given luminaire comprises more than one, but a plurality of individual lamps, wherein an individual controller and an individual coded light emitter are comprised in each individual lamp within the luminaire. For example, consider a luminaire for TLEDs, where each TLED individually includes its own separate respective driver, controller, CL modulator, and LED in the TLED. Such a scenario may occur, for example, where the luminaire itself is not designed from scratch or specifically upgraded to a "smart" or "connected" luminaire that accommodates a suitable lamp, such as an LED-based lamp, but where a retrofittable version of such a lamp has been retrofitted to a conventional luminaire designed only for a conventional "dumb" fluorescent tube or incandescent bulb. For example, in a typical office application, each luminaire may comprise four TLEDs. Solutions based on quick-fit connected TLEDs thus result in fourfold higher number of wireless nodes compared to competing solutions of applications or luminaire retrofit kits (e.g., philips evoxit products) or new coded light luminaires.

The illuminator typically also comprises a cavity (cavity) where there are many TLEDs in the illuminator, so light from different TLEDs will mix in the cavity before leaving the TLEDs. For example, this cavity is typically formed within a diffuser housing of the luminaire. Now if all TLEDs control themselves to emit coded light with different IDs, this will create a problem that the coded light signals will be superimposed out of phase with each other. Similar problems can arise with any type of retrofit lamp or any group of lamps having separate, independent coded light controllers and emitters within a given luminaire. It would be advantageous to prevent this, for example, so that a retrofit lamp in a multi-lamp luminaire can be used to encode light transmission to enable applications such as indoor localization.

Thus, according to one aspect of the present disclosure, there is provided a first lamp for use with one or more other lamps in a multi-lamp luminaire, each lamp being operable to emit a respective illumination embedded with a predetermined coded light message; wherein the first lamp comprises: one or more light emitting elements for emitting respective illumination intensities; a local controller; a communication interface configured to enable the local controller to communicate with a corresponding controller on each of one or more other lamps in the multi-lamp luminaire, the communication comprising sending and/or receiving one or more signals; and a coded light emitter operable to modulate a coded light message into the respective illuminance of the first light; wherein the local controller is configured to: based on communications via the communication interface, coordinate with corresponding controllers of one or more other lamps to prevent asynchronous instances of the encoded light message from being transmitted from different ones of the lamps in the multi-lamp luminaire. There are at least two alternatives for this: or the lamps coordinate to select the same message and synchronize to transmit this at the same time, otherwise the lamps coordinate such that only one of them transmits coded light.

Thus, in an embodiment, the local controller is configured such that said coordination comprises: coordinating such that each of the first lamp and the one or more other lamps transmits a respective instance of the same coded light message and synchronising all instances of said message to start transmitting at the same time. For example, one lamp plays the role of master lamp (master) based on the distributed protocol, and this master lamp then decides that it indicates the ID also used by the other lamps, and then causes the lamps to synchronize in order to align the transmissions in time (in time).

For example, the first lamp will typically include a mechanical connector for connecting to a complementary connector of the multi-lamp luminaire (preferably removably) to connect the one or more light-emitting elements to the power circuit of the multi-lamp luminaire to power the one or more light-emitting elements to emit the respective illumination intensities. In an embodiment, the first lamp may further comprise a timing circuit configured to use periodic variations in voltage and/or current of the power supplied by the power supply circuit (e.g. by detecting zero-crossing points) in order to derive a clock signal common to the first lamp and the one or more other lamps, wherein the coded light emitter is configured to synchronize the start of the respective instance of the coded light message to said clock signal, thereby synchronizing the start of the respective message to the start of the message transmitted by the one or more other lamps.

In an embodiment, the timing circuit may comprise a frequency divider (divider), wherein the coded light emitter is configured to derive the clock via the frequency divider such that the clock signal has a frequency lower than the periodic variation of the power supply (preferably, at least 8, or at least 16, or at least 32, or at least 50 or even 100 or more times, in order to convert an HF ballast frequency in the order of 20-100kHz to a coded light message retransmission rate in the order of 1-8kHz or even hundreds or tens of Hertz).

In an alternative embodiment, the local controller may be configured to select between operating the first lamp in an encoded light transmission mode in which the encoded light emitter transmits the message and a non-encoded light transmission mode in which the first lamp does not transmit any encoded light message; and (as mentioned) the local controller may be configured such that said coordination comprises: coordinating such that only one lamp among the lamps in the multi-lamp luminaire transmits a message and none of the other lamps among the lamps in the multi-lamp luminaire transmits any coded light, such that if a first lamp is to transmit said message, the local controller selects to operate the first lamp in a coded light transmission mode, and if one of the other lamps is to transmit a message, the local controller selects to operate the first lamp in a non-coded light transmission mode. I.e. all lamps in the luminaire agree on who emits coded light.

In this particular embodiment, the local controller may be configured to select between operating the first lamp in a plurality of different sub-states (substates) of the coded light transmission mode, each sub-state modulating the message into a respective illumination with a different modulation depth; and the local controller may be further configured to: detecting what number of other lamps are present in the multi-lamp luminaire based on the communication via the communication interface, and selecting between different sub-states depending on the detected number. Thus, advantageously, the overall modulation depth (as a proportion with respect to the total emitted illuminance from all lamps in the luminaire) does not have to be compromised by the fact that only one lamp emits a message. That is, assuming that all lamps emit their respective illuminations with the same intensity, but only one has a message modulated therein, the emitting lamp sets its modulation depth to a larger value (e.g., in intensity) when within the luminaire with a larger number of lamps than when within the luminaire with a smaller number (or even no) of other lamps. For example, if an emitting lamp is in a luminaire together with m other non-emitting lamps, it increases its modulation depth by a factor of m (e.g., in intensity).

In further embodiments, the local controller may be configured to receive a dimming signal indicating that the first light and the one or more other lights adjust the intensity of their respective illumination upwards or downwards; and the local controller may be further configured to, in response to the dimming signal: adjusting the respective illumination emitted from the first lamp (up or down, respectively) with a smaller scale relative to one or more other lamps with the first lamp in the coded light transmission mode; but with the first lamp in the uncoded light transmission mode, the respective illumination is adjusted (up or down, respectively) with a larger ratio with respect to one of the other lamps transmitting the message. This advantageously preserves some headroom (headroom) for the coded light modulation from the emitting lamp.

Regardless of the method by which coordination is achieved, in embodiments, the communication interface may be configured to perform said communication via a constrained signaling channel, whereby propagation of the one or more signals is constrained by physical properties of the luminaire, thereby limiting the transfer of the one or more signals only between those lamps in the same multi-lamp luminaire and not any other luminaires. That is, the luminaire has a containing or containment effect on the signal, acting as a physical barrier or obstacle, and based on this it can be ensured that: these signals are limited to lamps within the same luminaire.

In a particularly preferred embodiment, the constrained signaling channel comprises a power supply circuit (i.e. a ballast) powering the first lamp and the one or more other lamps, the communication interface being configured to perform said communication by modulating the current and/or voltage of the power supplied by said power supply circuit, the propagation of the one or more signals thereby being constrained to the power supply circuit within the same multi-lamp luminaire as the first lamp and the one or more other lamps. That is, a constrained signaling channel may be implemented with a signal transmitted (signal) through a power supply circuit (e.g., ballast) incorporated within the luminaire, i.e., so the signaling medium is the power supply circuit of the luminaire, and the physical feature that constrains the signal is the fact that the signal only travels through a local power supply circuit (e.g., ballast) within the luminaire and is therefore only passed to other lamps sharing the same power supply circuit. For example, the transmitting circuit may be configured to perform said modulation by modulating a load placed on the power supply circuit by the first lamp. This modulation may include, for example, on-off keying whereby the load is selectively shorted (short) or a switching power supply circuit is selected. In an embodiment, the power source for signaling is a ballast.

Alternatively, however, the constrained signaling medium may comprise coded light, ultrasound and/or radio, wherein propagation of the one or more signals is constrained by at least a portion of the housing of the luminaire.

In an embodiment, the first lamp may take the form of a retrofit LED-based lamp for replacing a fluorescent tube.

According to another aspect disclosed herein, there is provided a multi-lamp luminaire comprising a first lamp according to any of the embodiments set forth above or elsewhere herein and one or more further lamps. In an embodiment, one or more other lamps may be configured in the same manner as the first lamp (in terms of any one or more of the embodiments set forth above or elsewhere herein).

In an embodiment, the luminaire comprises a shared optical cavity in which the first lamp and the one or more other lamps are arranged. For example, the optical cavity may be formed within a diffuser of the luminaire.

According to another aspect disclosed herein, there is provided a method of operating a set of lamps in a multi-lamp luminaire, each lamp being operable to emit a respective illumination embedded with a predetermined coded light message, and each lamp comprising a respective local controller; wherein the method comprises the following steps: communicating between local controllers of lamps within a multi-lamp luminaire for coordination such that out-of-sync instances of the encoded light message are not transmitted from different ones of the lamps in the multi-lamp luminaire.

According to another aspect disclosed herein, there is provided a computer program product embodied on a computer readable storage medium and configured so as when run on a local controller of a first lamp to perform operations of the local controller.

In an embodiment, any of the first lamp, luminaire, method and/or computer program may further comprise features according to any of the teachings herein.

Drawings

To assist in understanding the disclosure and showing how embodiments may be put into practice, reference is made, by way of example, to the accompanying drawings, in which:

figure 1 is a schematic illustration of an environment in which a lighting system is deployed,

figure 2 is a schematic illustration of a luminaire comprising a plurality of lamps,

figure 3 is a schematic block diagram of a lamp,

figure 4 is a schematic wiring diagram for a luminaire with a plurality of lamps,

figure 5 is a schematic circuit diagram of a ballast,

figure 6 is a schematic circuit diagram of another ballast,

figure 7 is a schematic circuit diagram of a lamp,

figure 8 is a schematic timing diagram showing the current sensed by the lamp,

figure 9 is a schematic state diagram of a lamp,

figure 10a is a timing diagram showing the transmission of coded light messages from multiple lamps in an unsynchronized manner,

figure 10b is a timing diagram showing the transmission of coded light messages from multiple lamps in a synchronized manner,

FIG. 11 is a schematic circuit diagram of a lamp with zero-crossing detection circuitry and coded light synchronization, an

Fig. 12 is a schematic timing diagram illustrating the derivation of the clock signal from the HF ballast.

Detailed Description

Some exemplary embodiments for implementing VLC for TLED-based multi-lamp luminaires are described below. When two (or more) TLED tubes are within the shared optical compartment, the light output from the two tubes is mixed. In such a scenario, then no further measures are taken, and VLC pulses from different TLED tubes will be incorrectly concatenated; as a result, the coded light detection scheme cannot extract a correct VLC signal.

Embodiments disclosed herein provide a mechanism to set a single coded light ID for all TLEDs (or more generally lamps) within a luminaire and synchronize the coded light emissions of different tubes or lamps. Or alternatively, embodiments provide a mechanism to negotiate so that only a single lamp among the lamps in the luminaire emits the coded light ID. In either case, unsynchronized coded light transmission is thus avoided. In an embodiment, coordination between the lamps is achieved by communicating with each other via a communication channel constrained by the physical characteristics of the luminaire, e.g. by signaling via the ballast of the luminaire, such that communication can be assumed to be limited to only those lamps within the same luminaire.

Overview of the System

Fig. 1 illustrates an example lighting system in which the disclosed technology may be implemented. The system comprises one or more luminaires 4 mounted or otherwise deployed in an environment 2, which are arranged to emit illumination into that environment 2. The environment 2 may be an indoor space, such as one or more rooms and/or corridors of a building: or an outdoor space, such as a park, garden, road, or outdoor parking area; or partially covered spaces such as stadiums, structured parking facilities, or kiosks; or any other space, such as the interior of a ship, train, or other vehicle; or any combination of such possibilities.

Each of the luminaires 4 comprises at least one respective lamp, such as an LED-based lamp, an incandescent bulb, or a High Intensity Discharge (HID) lamp plus any associated supports, housings, or other such enclosures. Each of the luminaires 4 may take any suitable form, such as ceiling or wall mounted luminaires, floor luminaires, wall lamps, ceiling lights; or a less conventional form such as recessed lighting (devices) that are embedded into furniture, building materials such as glass or concrete, or any other surface. In general, the luminaire 4 may be any type of illumination device for emitting illumination into the environment 2. In an embodiment, the luminaire 4 is a device designed to emit an illuminance suitable for illuminating the environment 2, i.e. a functional lighting, designed and used to allow users to see and find their way within the environment 2, thereby providing or substantially contributing to adopting an illuminance of sufficient scale (scale) for that purpose. Nevertheless, without providing functional lighting (or also functional lighting), it is also possible that the luminaire 4 is a device designed to generate lighting effects such as task lighting, accent lighting or mood lighting; for example, a color changing recessed luminaire embedded in the surface.

An example of one of the luminaires 4 is shown in fig. 2. Each luminaire 4 comprises a power supply circuit 10, one or more lamps 12 and an outer envelope 14. In fact, at least one of the luminaires 4 and in embodiments some or all of the luminaires 4 comprise a plurality of lamps 12. In this case, the luminaire 4 comprises an internal power supply circuit 10 of the luminaire and a socket for connecting a plurality of lamps 12 to the power supply circuit 10 in order to power those lamps 12. For example, by way of example, FIG. 2 shows four lamps 12a, 12b, 12c, 12d in the same luminaire 4 (although it is noted that although the following embodiments may be described in terms of this example, this is not a limitation and the luminaire 4 may support other numbers of lamps 12). In this context in the same luminaire 4 means: the lamps in question share the same power supply circuit 10 and the same housing 14. Thus, the lamps 12a-d may be described as being "co-located" in the same luminaire 4. In general, "enclosure" 14 may refer to any housing and/or support structure of a light fixture. For example, in an embodiment, the enclosure 14 may include an opaque upper and/or side wall housing for mounting on a ceiling, plus a plurality of sockets mechanically coupled to the upper housing, and a lower diffuser element for diffusing the illumination downwardly emitted by the lamps 12a-d into the environment 2. However, in another example form, the "enclosure" 14 may take the form of a suspension structure (and the housing elements need not be present), such as a pendant-type structure that supports multiple receptacles.

The power supply circuit 10 is connected to an upstream power supply 16, e.g. a mains supply, and is configured to generate a power supply suitable for powering the lamp 12 based thereon. For example, the power supply circuit 10 typically takes the form of a ballast, i.e. a device for limiting the current supplied to the lamps in its luminaire 4.

In an embodiment, one or more of the illuminators 4 may each take the form of a fluorescent illuminator having a socket for receiving a plurality of fluorescent tubes (i.e., conventional gas discharge tubes). In this case, lamps 12a-d may take the form of "tube LEDs" (TLEDs), i.e. retrofit LED-based lamps designed to replace fluorescent tubes in conventional fluorescent luminaires designed for conventional fluorescent tubes. For example, most office luminaires employ 2-4 TLED tubes per luminaire (though not exclusively: some but not all other luminaires in the luminaire may have only a single TLED).

Table 1 shows an overview of the typical number of TLED tubes 12 and ballasts 10 per luminaire 4 for EMEA (europe, middle east and africa) and NAM (north america) regions. In almost all cases, only one ballast 10 is present per luminaire 4. In the USA, TLEDs 12a-d within the same luminaire are typically connected to a single fluorescent ballast 10.

Fig. 3 illustrates an individual TLED lamp 12 which may represent any of the lamps 12a-d used in the luminaire 4 described with reference to fig. 2.

As shown, the lamp 12 includes actual light-emitting element(s) 18, such as a string or other array of LEDs. The lamp 12 also comprises at least one end cap 20, and in the case of a TLED instead of a fluorescent tube, the lamp 12 in fact comprises two end caps 20i, 20 ii. Each end cap 20i, 20ii comprises a respective connector 22 for connecting the lamp 12 to the ballast 10, and thereby the light emitting element 18, via the socket of the luminaire 4 to the power supplied by the ballast 10. In the case of fluorescent tubes, each connector 22 in fact comprises two terminals (a pair of pins) which are either terminals that accept the filament, although in the case of TLED replacement fluorescent tubes, the two terminals of each connector are typically shorted together for instant start of the fixture, with no filament heating (but some impedance between the two pins is required for a programmed start fixture).

Further, at least one end cap 20i of the lamp 12 is used to mount additional components that are specific to the fact that the lamp 12 is a coded light emitting, wirelessly controlled, and/or LED-based replacement for a more traditional lamp, such as a fluorescent tube or incandescent bulb. These additional components include a rectifier 23 and an LED driver 24 for converting power supplied by the ballast 10 (designed to power conventional lamps such as fluorescent tubes) to power suitable for driving the LED-based lighting element 18. A rectifier 23 is connected to the connector(s) 22i, 22ii of the lamp 12 for receiving the AC power supplied by the ballast 10 and converting it to DC. The LED driver 24 is connected to the rectifier 23 and is arranged to further convert this into an approximately constant (but in embodiments, adjustable) current source for powering the LED-based lighting element 18 (e.g., LED string) and thereby causing a desired light output to be emitted from the lighting element 18. Note that: the rectifier 23 is not required if the power supplied by the power supply circuit 10 of the luminaire is already DC, but typically in the context of a retrofit LED-based lamp, the power from the luminaire's own power supply circuit (e.g. ballast) 10 will indeed be AC and therefore need to be rectified.

Further, additional components in the end cap 20i include a controller 26 and optionally a wireless interface 28 employing a radio transceiver, such as a ZigBee, Wi-Fi, 802.15.4, or Bluetooth transceiver. The controller 26 may be implemented in software stored in an embedded memory of the lamp 12 and running on an embedded processing device 46 of the lamp 12, or the controller 26 may be implemented in a dedicated hardware circuit or a configurable or reconfigurable hardware circuit such as a PGA or FPGA. In an embodiment, the controller is implemented in a combination of software and dedicated hardware M1 (see fig. 7, discussed in more detail later).

In an embodiment, to assist in installation for optimal communication between lamps 12 within luminaire 4, end cap 20i housing the add-on components may be marked with physical (e.g., visible) marking(s). For example, a physical marker may be provided on the end where the radio is located, and the installer may be instructed to group markers within the luminaire. Alternatively, color coding can be used, with one color of indicia on one end 20i and another color of indicia on the other end 20 ii. E.g., a red dot on one cover (and optionally a blue dot on the other cover), and may provide instructions for the same colored covers to be put together.

The controller 26 is connected to the wireless interface 28 and the LED driver 24. The controller 26 is configured (e.g., programmed) to use the wireless interface 28 to receive lighting control commands from a manual or automatic lighting controller (not shown), such as a dedicated remote control device, a wireless wall switch or wall panel, or a lighting control application running on a user terminal like a smartphone, tablet, laptop, or desktop computer. In response, the controller 26 then controls the driver 24 to control the light output of the light emitting elements 18 in accordance with the received control commands. This may include, for example, turning light on or off, dimming the light output up or down, changing the color of the light output, or creating a dynamic (time-varying) lighting effect. For example, the controller 26 can adjust the current levels supplied to the LEDs in the light emitting elements 18 to adjust the light output, and/or can adjust the current levels supplied to different color LEDs or sub-arrays among the LEDs in the light emitting elements 18 to adjust the overall color of the light output.

Alternatively or additionally, in a distributed system, each of the luminaires 4 may comprise one or more sensors, such as an ambient light sensor and/or an occupancy sensor (not shown), and/or one or more wireless sensors may be placed elsewhere in the environment 2. In this case, the controller 26 may be configured to use the wireless interface 28 to receive sensor readings from one or more sensors, for example, in the same luminaire 4 and/or adjacent luminaires 4. In response, the controller 26 can then control the light output of the light-emitting elements 18 as a function of the sensor reading(s), for example, to dim or turn off the light when the sensor detects an ambient light level above a threshold or the absence of occupants being present within a predetermined vicinity, or to dim or turn on the light when the sensor detects an ambient light level below a threshold or the presence of occupants in a vicinity (or more generally, the control can be based on a more complex distributed control algorithm that calculates adjustments based on sensor readings from multiple sensors).

In further embodiments, the controller 26 may also be configured to use the wireless interface 28 to send status reports to a lighting controller (not shown), such as reporting a burning hour to date (burning hours), reporting an operating temperature of the lamp, and/or reporting a fault.

However, this first requires the lamp 12 to be commissioned in order to be able to perform the various activities discussed above or the like. That is, the lamp 12 needs to be identified and added to a wireless network, such as a ZigBee, Wi-Fi, 802.15.4, or Bluetooth network. This wireless network then provides a means by which the wireless interface 28 on each lamp 12 can then be used to receive lighting control commands from a lighting controller (not shown), receive sensor readings from the sensor(s), and/or send status reports to the lighting controller during the operational phase. The following will be described in terms of ZigBee, but it will be appreciated that: this is not necessarily a limitation.

Preventing asynchronous transmissions

It would be desirable to include coded light functionality also in a retrofit LED-based lamp such as a TLED or the like, for example, to enable indoor location applications for food and large retail industries based on coded light quick-fit TLEDs. By utilizing a quick-fit TLED or other such retrofit lamp for coded light applications, such as indoor positioning, this advantageously allows for faster upgrades of the lighting system to include coded light functionality by relamping rather than replacing or retrofitting the luminaire 4 itself. The following embodiments may be described by way of example in terms of TLEDs, but it will be appreciated that: in general, similar teachings can be applied to other retrofit LED-based lamps (e.g., replacement for incandescent light bulbs) or to coded light emitting lamps.

In an embodiment, it would be desirable to provide a TLED product that emits a fixed factory set VLC code unique to the luminaire in which the TLED is installed. The appeal of VLC TLEDs is a high cost competitiveness of the underlying TLED platform, both with respect to component cost and ease of installation. Adding coded light functionality to a non-intelligent TLED results in a rather limited cost rise, approximately 10% extra BOM (bill of material) cost; which is low compared to the potential value generated due to indoor localized retail applications. Alternatively, a ZigBee based wireless TLED encoding an optical version may also be attractive, for example, for being an enabler for easier commissioning.

Coded light TLEDs emitting VLC codes work well when applied to installations with only single tube luminaires such as bare lamps (bare lamp). However, if two TLEDs are placed within a shared optical capsule, the light from the two tubes will be mixed. Since VLC pulses from different tubes will be concatenated incorrectly, the coded light detection scheme cannot extract VLC signals for these tubes. Again, similar comments may apply to other types of coded light emitting lamps as well.

To address this issue, embodiments of the present disclosure provide a mechanism to group (preferably automatically group) all tubes within the same optical chamber and then automatically synchronize their coded light patterns. For example, the process may be as follows:

I) determining which lamps 12 are located within the same luminaire 4 (either automatically based on determining spatial proximity (proximity), or by other means, such as via a commissioning tool, e.g. a ZigBee or NFC near field communication configuration tool);

II) assigning the same coded light ID (e.g. via a commissioning tool such as ZigBee or NFC tool) for two (or all) of the lamps 12a-12d found within the same luminaire 4; and

III) synchronizing the coded light emission patterns of the lamps 12a-12d by communicating between the lamps in the same luminaire. Alternatively, the lamps 12a-12d may negotiate such that only one of them emits coded light, while the other lamps emit only uncoded illumination.

In an embodiment, the spatial proximity of the lamps is detected using a measurement of received signal strength or time of flight of a signal emitted from one TLED and detected by another. The signal for determining the spatial proximity can be a visible light, invisible light, radio, thermal, audio or ultrasonic signal. Or in a variant of this, the spatial proximity may be detected by emitting a signal from at least one lamp 12a on a "constrained signalling channel", so that the propagation of the signal is constrained by the physical properties of the luminaire 4, so that it is received only by those other lamps 12b-12d which are found in the same luminaire. In this way, these lamps 12 are able to detect with which other lamps they share the luminaire 4.

In an embodiment, this (or some) constrained signalling channel may also be used to perform the communication between the lamps 12a-12d within the luminaires 4 required for mutual coordination to ensure that they emit the same code at the same time or that only one of the luminaires 4 emits a code.

Fig. 11 illustrates an example TLED circuit in accordance with embodiments disclosed herein. In addition to the components already described with reference to fig. 3 (and described later with reference to fig. 7), the circuit includes a coded light modulator 76 and a modulator switch 70 and optionally a zero-crossing detector 72 and a frequency divider 74 in the form of a counter. The modulation switch is coupled to, e.g., coupled in series with, one or more light-emitting elements (in this case, LEDs) 18. The coded light modulator 76 is coupled to the modulation switch 70 and is arranged to switch the modulation switch 70 to thereby modulate an attribute, such as the intensity of illumination emitted by the one or more light-emitting elements 18. The microcontroller 46 is coupled to the coded light modulator 76 and is configured to control it so as to modulate the illumination emitted by the one or more light-emitting elements 18 via the modulation switch 70. In particular, the microcontroller 46 is configured to control the modulator 76 to modulate the illuminance so as to embed a message (i.e. data or signal) into the illuminance, e.g. a code to be used as the ID of the luminaire 4.

Note that: although an on-off switch is shown in fig. 11 for illustrative purposes, in embodiments, the modulation need not be included between fully on and fully off but rather to switch the illumination between two non-zero levels such as, for example, between +10% and-10% of the nominal intensity. Or in other embodiments more than two levels may be used, or even continuously variable modulation can be used. The various coded light coding schemes will be known per se to the person skilled in the art and will therefore not be repeated here in great detail.

In an embodiment, coded light modulator 76 is configured to derive a clock signal from High Frequency (HF) oscillations in the voltage and/or current supplied by ballast 10 to lamp 12, and to time the transmission of the coded light message according to this clock signal. To this end, in an embodiment, the zero-crossing detector 72 is coupled to one of the input lines 22 connected to the ballast 10 and is configured to output an assertion (assert) whenever a zero-crossing is detected in the sinusoidally varying voltage or current supplied on this line 22i/ii from the ballast 10. Preferably, the output of the zero crossing detector 72 is coupled to the input of a frequency divider 74 comprising a counter. In this case, the counter 74 is clocked each time a positive assertion is output from the zero-crossing detector 72. The counter 74 has a counter length of some predetermined number, e.g. if it is a four-bit counter, it has a length of 16, i.e. it cycles through 16 counter values from zero to 15. Each time the counter 74 cycles around this number of counts, it outputs a positive assertion (logical true signal) to the encoding light modulator 76. Thus, the counter 74 divides the frequency of the signal output from the zero-crossing detector 72 (which is equal to twice the HF frequency of the ballast) by a predetermined number such as 16. The coded light modulator 76 may be configured to transmit coded light messages that are repeatedly triggered by the output of the frequency divider 74, i.e., once per positive assertion from the frequency divider 74 (once per logical true). Note that: although described herein in terms of a TLED ballast 10, the same principles can be applied to any lamp having a power cycle or periodic component to it.

In a first class of embodiments, the microcontrollers 46 on the different lamps 12a-12d are configured to coordinate with each other in order to synchronize the coded light emission of these lamps 12a-12 d. In particular embodiments, the communications involved in doing so may be achieved through communications via a "constrained signaling channel". That is, the communication channel is constrained by the physical characteristics of the luminaire, such that propagation of the signal is limited by the physical properties of the luminaire. Thus, the signal is received by only those lamps 12a-d within the same luminaire 4, but not other lamps 12 that may be present in the environment outside the luminaire 4 in question. This may be achieved, for example, by means of a signal modulated into the voltage and/or current of the power supply circuit powering the respective group of lamps 12a-12d in the respective luminaire (e.g., via load variations of the ballast 10). As another example, the constrained channel can be implemented by signal transmission using coded light, radio or ultrasound, wherein at least a portion of the housing of the luminaire 4 is arranged to be shielded to prevent propagation of signals outside the luminaire 4. Details of examples for implementing the constrained signaling channel will be discussed in more detail later.

Thus, if the lamp 12 (or more precisely its microcontroller 46) signals through this channel, it can be assumed that: only other lamps in the same luminaire will receive them. Similarly, if a signal is received by a lamp 12 through such a channel, it can be assumed that this (signal) comes from another lamp in the same luminaire 4. Thus, by communicating over such a channel, it is possible for a lamp 12 to detect which other lamps are its siblings in the same luminaire 4. For example, the lamp 12 may be configured to detect adjacent lamp assemblies by: a signal is received from that component on a restricted channel at commissioning or in response to detecting a new lamp when an old lamp is replaced at a later stage after commissioning.

Furthermore, in an embodiment, the lamps 12 (or more precisely their respective microcontrollers 46) are arranged to communicate with each other over this type of channel in order to perform the coordination required between the lamps 12a-12d in the same luminaire 4 to ensure that they all emit the same coded light message. The HF output of the legacy fluorescent ballast 10 can then be used to derive a synchronous clock signal, for example, based on the techniques described above. Since only the lamps connected to the same fluorescent ballast 10 are exposed to the power output of this ballast, this means: they all derive the same synchronized clock signal with the same time alignment and are therefore each triggered to simultaneously transmit their respective instances of the encoded optical message. According to one implementation of this, as mentioned, the zero-crossing detector 72 may be arranged to detect zero-crossings of the high frequency output of the fluorescent ballast 10, and the counter 74 may be used to reduce the frequency of the synchronization signal (e.g., by dividing the HF oscillation by an integer).

As an alternative variant of this, the synchronization may be achieved by signaling from one lamp 12a to the other lamps 12b-d over the (or some) constrained signaling channel, e.g. modulation of the voltage and/or current again via the power supply circuit 10. In this case, the controller 46 on one master lamp (e.g., 12 a) is configured to actively send a synchronization signal to the other lamps 12b-12d in the luminaire that indicates the timing used by the master lamp 12a to transmit its respective instance of the coded light message, and the other lamps 12b-d (or more precisely their controllers 46) use the synchronization signal to time the transmission of their respective instances of the message to coincide with the transmission of the message from the master lamp 12 a.

Note also that: although the preferred embodiment uses a constrained signaling channel to detect both which lamps are in the same luminaire and the communication involved in coordinating between these lamps, this is not essential in all possible embodiments. Alternatively, for example, the constrained signalling channel may be used initially only at commissioning to detect which lamps 12 are in the same luminaire 4, and then based on this, as part of the commissioning process, the addresses of those lamps within an RF wireless network such as a Wi-Fi or ZigBee network may be determined. These addresses may then be stored in the locations visited by each lamp 12, together with an indication that the lamps with those addresses share luminaires (e.g. each lamp stores the address of each other lamp locally in its own embedded memory, or these addresses are stored centrally in a lamp-luminaire mapping database in locations such as a server accessible to each lamp 12). Then, once these network addresses are known and stored, the microcontrollers 46 on the lamps 12 in the same luminaire 4 can use these to communicate with each other over an RF network, for example a Wi-Fi or ZigBee network, via the respective wireless interfaces 28.

Or as a further alternative, there is no need to use a restricted signaling channel at all. For example, proximity between lamps may be detected by emitting a wireless signal from at least one of the lamps (e.g., 12 a) and then measuring a distance-related property such as the received signal strength or time of flight of the signal received on each of the other lamps 12 within range of the signal. This can be, for example, an RF, ultrasonic, visible, infrared or ultraviolet signal. Based on a predetermined knowledge of the distance between the lamps in the luminaire 4, the controller 46 of the lamps or a commissioning tool or commissioning technician can then determine which lamps 12a-12d are found in the same luminaire 4 and store the addresses of these lamps. As yet another possibility, which lamps 12 share a luminaire can be detected based on Near Field Communication (NFC) technology embedded in each lamp 12 or can be determined manually by a commissioning technician.

A step-by-step description of the preferred embodiment now follows.

The first step is to identify a main lamp within the same luminaire 4. This can be achieved in a number of ways, for example by means of an installer operation via NFC or by means of an automated process such as via a constrained signalling channel. In an embodiment, each given lamp 12 is capable of operating in either a master or slave mode. In the master mode, lamp 12 generates a synchronization and optionally a coded light ID, while in the slave mode, lamp 12 receives a synchronization signal and an ID from the master lamp.

In an embodiment, the microcontroller 46 on the lamp 12 is configured to operate according to a distributed protocol to determine which of them become master lamps and which are slave lamps. The selection may be made once at commissioning or in a continuous manner, e.g. periodically or in response to some event, such as an old lamp within the luminaire 4 being replaced by a new lamp.

In an embodiment, the distributed protocol may involve negotiation between microcontrollers 46 on different lamps 12a-12 d. In an embodiment, this negotiation may be done via a constrained signaling channel (e.g., by signaling via ballast 10) so that the lamps 12 know that they are negotiating between only their neighbors in the same luminaire 4. Alternatively, if the addresses of the lamps 12a-12d within the same luminaire 4 are known with respect to each other (or rather their microcontrollers 46), the negotiation may be done via other means, such as via a wireless RF network and the wireless interface 28. In some particular embodiments, determining which lamp 12 is the master may involve a respective random delay before each lamp 12 begins signaling; until the point (time) at which the random delay period ends, the microcontroller 46 at each given lamp 12 has to listen (listen to) to signals from other lamps in the same luminaire 4 and first listen to what becomes dominant. The lamp 12 may follow the ALOHA protocol for collision avoidance. A specific example protocol for selecting which lamps 12 within the luminaire 4 will become master lamps and which will become slave lamps will be described in more detail later. However, this is not a limitation, and in general, those skilled in the art will appreciate other suitable distributed master-slave protocols that a set of components can utilize to determine which of them will be the master and which will become the slave of the master.

As will be described below, as if the first lamp 12a had been selected to become the master lamp and one or more of the other lamps 12b-d had been selected to become the slave lamps. However, it will be appreciated that this is by way of example only: in an embodiment, each lamp 12a-d is identically configured at the time of fresh "out of the box," and each lamp may have an equal chance of becoming a main lamp.

As a second step after selecting the main lamp, the main lamp 12a will start synchronization (e.g., after power up). In addition to synchronizing the coded light emission, the main lamp 12a may optionally also set up that a single coded light ID is to be emitted by all lamps 12a-d within the luminaire 4. In an embodiment, each of these actions is preferably accomplished by signaling from the microcontroller 46 of the master lamp 12a to the respective microcontroller 46 of the slave lamps 12b-d over a constrained signaling channel, such as by modulating the signal into a shared power supply, e.g., via the ballast 10. Alternatively, however, this can be achieved via other means, such as via a wireless RF network and a wireless interface 28, if the addresses of the lamps 12a-12d within the same luminaire 4 are known to each other.

As a third step, the master lamp 12a and each of the slave lamps 12a-12d use the HF output of the ballast 10 as a clock signal to ensure that: the VLC signals for the lamps 12a-12d remain synchronized over time. This is illustrated in fig. 11 and 12.

As shown, the input of zero-crossing detector 72 of each lamp 12 is coupled to point a on one of the respective power input lines from ballast 10. The zero crossing detector 72 detects zero crossings in the HF power supply by sensing the voltage across the input rectifier of the lamp 12. This detection signal from a approximates a square wave, but the zero-crossing detector is also configured to convert the edges of the square wave into pulses, labeled "zcd" in fig. 12.

However, typical HF ballast output frequencies are between 20kHz and 100 kHz. This frequency is too high for simple coded light applications. To address this, the counter 74 is arranged to generate a lower frequency pulse stream "sync _ ck" based on the HF signal. That is, the zcd signal pulses are used as an input clock signal to the counter 74, which clocks the counter 74 so that with each input pulse it increments by one up to a predetermined upper value, after which the counter 74 resets and again starts counting from a predetermined lower value, typically from zero (or likewise the counter can count down from the upper value to the lower value). The counter 74 is configured to generate a pulse on its output each time it cycles between an upper and lower value, thus generating a series of pulses at a lower frequency than that supplied by the zero-crossing detector 72.

The output of the counter 74 is used as a synchronizing clock signal for the VLC modulator 76. For example, assume the counter is an m-bit counter. The frequency of the synchronization signal is then the ballast output frequency divided by 2^ m. For reliable operation of VLC, the synchronization signal should preferably be of the order of tens of Hertz. As an example implementation, an embodiment may use a 2KHz symbol clock, where 24 bits are repeated continuously, including 16 bits of data and an 8 bit CRC. Thus, each message takes 35ms (milliseconds) (about the frame time of the smartphone camera).

Each time the coded light modulator 76 on each of the master and slave lamps 12a-12d detects a pulse from the output of the counter 74, it is triggered to emit an instance of a coded light message assigned by the master lamp 12 a. Thus, the start of each instance is aligned in time with the other instances. Further, when each microcontroller on each slave is instructed by the master to transmit the same message (e.g., the same ID code), then each outgoing instance of the message from each of the master and slave lamps 12a-12d is the same, each having the same length and each comprising the same sequence of the same symbols (e.g., bits). The modulation switch 70 modulates the LED current and thus the light generated by the lamp 12. Thus, by having all lamps connected to the same ballast generate a synchronization signal for VLC using the same HF signal, it is possible to use the HF input signal from the ballast as a means for keeping the coded light messages from the lamps 12, such as TLEDs, synchronized.

This is illustrated in fig. 10b, in contrast to fig. 10a, which shows an out-of-sync situation. If there is no synchronization, the instances of the code from different lamps 12a-12d will all start transmitting at different times, even if the lamps 12a-12d are arranged to emit the same code (or this may not be guaranteed). When the lamps 12a-12d are also in the same luminaire that shares the same optical cavity (e.g., the same diffuser), then the light from the different lamps 12a-12d carrying the code will be destructively mixed together, and the code may thus be difficult or even impossible to detect and decode by the coded light detector. However, with synchronization as shown in fig. 10b, instances of the code are constructively added and thus detection is possible.

In an alternative variant of the above, each of the lamps 12 may also be equipped with a quartz clock (not shown). However, the quartz clocks of the lamps 12a-d, such as the TLED tubes, drift (drift) relative to each other. In an embodiment, the coded light modulator 76 in each lamp 12a-12d may be arranged to time the transmission of messages on the basis of a quartz clock, but also to synchronize the coded light signals of the lamps 12a-d within the same luminaire 4 periodically, e.g. hourly, based on signals exchanged between the respective microcontrollers 46 over a constrained signaling channel.

In a second alternative class of embodiments, the above second step may be omitted. In that case, after determining the master lamp 12a within the luminaire 4, then the transmissions from the various lamps 12a-12d in that luminaire are not synchronized, but instead only this master lamp 12a emits coded light, while the slave lamps 12b-d only emit a constant illuminance output without coded light. For example, the master light may explicitly indicate that the slave light is not emitting coded light, or the slave light may be configured to implicitly understand: once they have determined that they should enter the slave mode, they should not emit coded light.

Again, in an embodiment, the communication involved between master lamp 12a and slave lamps 12b-d imposing this state of affairs(s) may be conducted over a constrained signaling channel, for example, by modulating signals into the power supply shared by lamps 10, such as via ballast 10. Alternatively, this communication can be done via other means, such as via a wireless RF network and a respective wireless interface 28, if the addresses of the lamps 12a-12d within the same luminaire 4 are known with respect to each other.

Note that: in some embodiments of this second category, additional measures may be taken to ensure that the illumination function of the luminaire 4 is not impaired by the fact that only one lamp 12a and no other lamps 12b-d are emitting coded light messages.

For example, in an embodiment, the microcontroller 46 may be configured such that when the main lamp 12a is controlled to emit coded light while the other lamps are in a "no-emission" mode, then the microcontroller 46 will detect how many lamps 12a-12d are present in the same luminaire 4 and adapt (adapt) the modulation depth of the coded light emitted by the main lamp 12a accordingly (modulation depth is the difference between the maximum and minimum modulation levels of the intensity, typically the property of the symbols modulated to represent the message, i.e. thus the difference between the maximum and minimum intensity). That is, the main lamp 12a is configured to set its modulation depth to 2, 3, … … or k times the single lamp level if the number of lamps 12 in the luminaire 4 is 2, 3, … … or k, respectively. The reason for this is: the modulation depth should preferably be scaled (scale) so as to be detectable among the amounts of uncoded light emitted by the other lamps 12b-d in the illuminator 4. For example, in the case of two TLEDs, the master TLED will adjust its modulation depth to twice its normal or nominal value (twice the depth that would be used if emitting alone), so that the total modulation depth of the combination of master and slave TLEDs reaches the value desired for the application, and the same proportion of the total light level is maintained as if only one TLED is currently emitting coded light at the normal or nominal value.

In alternative or additional embodiments, the microcontroller 46 may be configured such that its response to a dim command depends on whether it is currently playing a master role of emitting coded light messages or not (where the dim command can come from a user input device such as a dimmer switch or a lighting control application running on a user terminal, or from an automatic lighting control apparatus such as from a centralized building or lighting controller or from a local or remote sensor). In particular, microcontroller 46 is configured such that it dims its illumination output to a lesser degree when its lamp 12a is the master and to a greater degree when its lamps 12b-d are the slave, but such that the overall response to the dim command from all of the lamps 12 in the combined luminaire 4 still conforms to the dim command (i.e., the overall illumination is still dimmed up or down by the amount specified by the dim command). The reason for this is: if there are k lamps being dimmed and these lamps are emitting coded light, there is a risk that the (per lamp) headroom for the coded light (amplitude) modulation becomes too low. To avoid this, it may be desirable to coordinate dimming among the lamps. Thus, the lamp 12 (or more precisely the microcontroller 46 thereof) may select one or two lamps for less dimming, in order to maintain a headroom for the coded light emission, and in order to compensate for more dimming of some of the other lamps. This is particularly relevant when the light is mixed by an element such as a diffuser before exiting the luminaire 4 (and is therefore less relevant in the case where the lamp 12 is in front of the eye).

In still further alternative or additional embodiments, the microcontroller 46 of the lamp 12 may be configured to provide automatic fail-over for the case where only one lamp 12a emits coded light and the other lamps 12b-d are set to "no emission". That is, the microcontrollers 46 on the other lamps 12b-d are configured to detect whether the coded light emitting lamp 12a is malfunctioning (e.g., detect this via a constrained signaling channel or via an RF wireless network), and if so, operate such that one of the "no emission" lamps 12b-d begins emitting coded light (using a negotiation or distributed protocol to determine which lamp if there are more than two lamps in the luminaire, e.g., negotiation on a constrained signaling channel or an RF wireless network). Also, if the broken lamp 12a is replaced by a factory new lamp, no action is required by commissioning personnel.

Automatic packet & master/slave roles

The following describes a commissioning method which among other aspects (the amplitude other aspects) comprises a distributed protocol for selecting which lamp among a plurality of lamps 12a-12d in the multi-lamp luminaire 4 will act as a master lamp (or "leader") and which lamp will act as a slave lamp (or "follower"). The described protocol for selecting master and slave lamps may be used, whether or not the other characteristics described below come with it, in order to determine which lamp 12 will become the master lamp for the purpose of deciding on the coded light ID (in embodiments where all lamps 12 in the luminaire 4 issue IDs), or which is the master lamp in the sense that it will emit coded light messages of other lamps (in embodiments where only one lamp among the lamps 12 in the luminaire 4 issues an ID). The process of deciding who will be the main lamp may be performed in an ad-hoc manner during and/or after a commissioning phase, e.g. triggered periodically or in response to a new lamp being added to the luminaire (relamping).

An optional procedure that can be used to detect which lamps 12a-d share the same luminaire 4 at commissioning and to automatically group these lamps is also described below.

As mentioned, one type of connection lamp is a quick-fit "tube LED" (TLED) lamp, which is retrofitted to an illuminator designed for a conventional fluorescent tube. According to the fast-match TLED scheme, all electrical connections within the existing fixed-output fluorescent ballast, TLED lamp socket and also the luminaire remain unchanged. Via straightforward re-lighting, existing "dummy" fluorescent tubes (or even "dummy" TLED tubes), each with an individual integrated radio station, can be exchanged with dimmable connections TLEDs.

However, replacing all items of legacy pipe in the office with TLEDs or the like would require a commissioning process.

Consider a process of commissioning an arrangement of wireless luminaires in which a wireless interface is included in the housing of each luminaire on a per luminaire basis (rather than the wireless interface being included in each individual wireless lamp). To do so, the commissioning technician has to stand under (or in the visible vicinity of) each luminaire that he or she intends to commission, and select the luminaire he or she believes to be on the user interface of the commissioning tool (e.g., a dedicated commissioning device or a commissioning application running on a mobile user terminal such as a smartphone, tablet or laptop). The commissioning tool then broadcasts a commissioning request that includes the identifier of the selected luminaire, and the luminaire with that identifier in the response will issue a visual indication (e.g., by flashing via its light(s) or a separate indicator light). In this way, the technician can check whether the selected luminaire is indeed the luminaire he or she intends to debug. If so, the technician then confirms this to the commissioning tool, and in response, the tool adds the confirmed luminaires to the wireless network in order to control the lights in subsequent phases of operation. The commissioning technician then repeats this for each luminaire to be commissioned (e.g., each luminaire in the office).

As an alternative, sometimes the pointing method is also applied to identify a specific luminaire during the commissioning process. One example is an infrared remote control directed to a luminaire featuring an infrared receiver. Another approach is to select luminaires by shining high power torch light (torchlight) to the daylight sensor of a particular luminaire.

Consider now the case where a wireless interface is included in each individual wireless lamp. In a typical office application, each luminaire comprises four TLEDs. Solutions based on a quick-fit connection TLED thus result in four times higher number of wireless nodes than competing solutions applying or wireless luminaire retrofit kits (e.g., philips evoxit product) or new wireless luminaires. Thus, due to the very high number of wireless nodes per space, the current state of the art solutions for connecting TLEDs will result in very high commissioning effort. That is, the commissioning technician would have to perform the above steps for each lamp, not just for each luminaire, by standing under or in visible proximity to each individual lamp and flashing it to confirm its identity, and then individually joining each lamp to the control network. The commissioning technician may also have to identify which lamps are part of the same luminaire in order to allow them to be controlled (e.g. dimmed) as a group after the commissioning phase is over. Further, such procedures typically require a relatively highly skilled commissioning technician.

The following provides an auto-commissioning method for the automatic grouping of multiple connected TLED tubes or other such wireless lights that are residing within the same luminaire. In an embodiment, the automatic grouping method builds on the insight that TLEDs residing within the luminaire are wired to one shared fluorescent ballast. To take advantage of this, verification that TLEDs share the same ballast is performed via an intentional load change pattern impressed (imprint) onto the ballast with one master TLED. The load variations experienced by the fluorescent ballast cause a shift (shift) of the ballast frequency and/or lamp current provided by the fluorescent ballast towards other slave TLEDs within the lamp, depending on the ballast type. Upon detection of a frequency or current shift pattern caused by the master TLED, each of the one or more slave TLEDs can conclusively conclude that: it shares the same ballast and therefore it is within the same luminaire as the master TLED.

The following disclosure also provides a network join mechanism optimized for TLED. Initially, only the Master Connected TLED is visible to the installer as Factory New lights. Once the installer adds the Master TLED to the ZigBee network established by the lighting bridge or remote control, the slave TLEDs residing within the same luminaire are enabled to also join the same ZigBee network without any additional action from the installer. The present disclosure further provides a "ballast-load-drop-based" automatic grouping method that aims at replacing a broken connection TLED without requiring installer intervention.

To increase the speed of TLED automatic grouping, the program preferably starts with a faster and less intrusive (but less deterministic) evaluation method. That is, first, TLEDs within the same luminaire can be assumed to be likely within a relatively small "wireless" vicinity, as compared to typical spacing for nearest neighbor luminaires. Thus, based on radio RSSI (or alternatively coded light), TLEDs may be grouped into buckets, such as "likely to be within the same luminaire", "unlikely to be within the same luminaire". Then, starting from the initial RSSI-based TLED bucket, the method continues using load modulation to determine unambiguously which of the TLEDs are connected to the shared fluorescent ballast and therefore certainly located within the same luminaire.

According to embodiments disclosed herein, the controller 26 is configured to participate in a debugging process prior to the operational phase. Commissioning involves one or more of these lamps 12 interacting with the commissioning tool 6 used by the user 8 who is performing the commissioning. The commissioning tool 6 may take any suitable form, such as a dedicated remote unit or a commissioning application running on a user terminal such as a smartphone, tablet or laptop computer. Note that: the commissioning tool is typically not the same device as a lighting controller (not shown) which then controls the lamp 12 in an operational phase, although that possibility is not excluded.

The user 8 uses the commissioning tool 6 to at least initiate commissioning of each of the luminaires 4 that he or she wishes to pull into the control network, although some or all of the remainder of the process may then proceed in an automated manner between the lamp 12 and the commissioning tool 6 according to embodiments disclosed herein.

The controller 26 on each lamp 12 is configured to be able to operate its respective lamp 12 in either a Factory New (FN) mode or a non-factory new (non-FN) mode and switch between these modes. These may be, for example, the FN and non-FN modes of the ZigBee Light Link protocol. In FN mode, the lamp 12 appears to the commissioning tool 6 to be awaiting commissioning. This may be accomplished, for example, by the controller 26 repeatedly (e.g., periodically) sending out beacons using its respective wireless interface 28, where the beacons advertise: the respective lamp 12 is waiting for commissioning. Alternatively, this may be achieved by: the controller 26 sets itself to respond to the query broadcast from the tool 6 to answer: the lamp 12 is waiting for commissioning. In the non-FN mode, the lamp 12 does not. For example, the controller 26 does not issue any beacons or at least does not issue beacons that advertise the lamps 12 as awaiting commissioning (e.g., it can stop issuing certain beacons or change the content of its beacons so as not to declare that the respective lamps are awaiting commissioning). Alternatively, the controller 26 may set itself to a mode in which it does not respond to a query broadcast from the tool 6 or replies with a response that the lamp 12 is waiting for commissioning.

Thus, when the lamp 12 is in FN mode, the commissioning tool 6 detects the lamp 12 as awaiting commissioning and displays it as such to the user 8 through the user interface of the commissioning tool 6. On the other hand, in non-FN mode, the commissioning tool 6 will not see the lamp 12 as waiting for commissioning and therefore will not display it as such to the user 8 through the user interface of the commissioning tool 6.

In an embodiment, waiting for debugging means at least: waiting to be joined to a wireless network (e.g., a ZigBee network) for the purpose of subsequent control in an operational phase. Thus, in an embodiment, the controller 26 on each lamp 12 is configured to: the beacon is issued when in FN mode but stops issuing when in non-FN mode, or in an alternative embodiment, changes the way it responds to a query broadcast from a commissioning tool searching for lamps 12 awaiting commissioning. By way of illustration, the following example may be described in terms of previous implementations, where FN mode controls whether a respective lamp 12 is beaconing (or at least whether it is beaconing that advertises that it is waiting for commissioning). In the latter implementation, if the commissioning tool 6 issues an offer (offer) for an open network, the controller 26 of the master lamp will react to the offer, but the slave lamp will ignore the offer.

Another attribute utilized by embodiments herein is: a lamp configured according to the ZigBee standard, such as the ZigBee Light Link standard, will automatically switch from FN mode to non-FN mode when it joins the ZigBee network. Thus, according to embodiments herein, causing lights to join and leave the temporary network can be used to manually manipulate FN patterns.

According to the example techniques disclosed herein, the controller 26 on each of the lamps 12 is configured to adhere to a distributed master-slave protocol whereby it determines in a distributed manner (without involving coordination by a centralized controller) whether itself will become a master or slave (controller) for commissioning purposes. The protocol is arranged such that one and only one lamp 12a per luminaire 4 will become the master lamp and all other lamps 12b, 12c, 12d in the same luminaire 4 will become the slave lamps of the respective master lamps 12a (note: the 12a tagged lamp is described herein by way of example only as a master lamp, in general the master lamp can be any one of the lamps 12a-d in the same luminaire 4). Techniques for detecting which lamps 12a-d are within the same luminaire will be discussed in more detail later.

The controller 26 of lamp 12a, which becomes the master, then manually manipulates the FN mode of its slave lamps 12b-d so that all lamps except the master lamp 12a are hidden in the user interface of the commissioning tool 6 and not displayed to the user 8. This is achieved by having the master lamp 12a cause the slave lamps 12b-d to join a temporary wireless (e.g. ZigBee) network created by the master lamp. Further, the controller 26 of master lamp 12a performs one or more commissioning operations on behalf of itself and its slave lamps 12b-d as a group. Thus, from the user's point of view, commissioning is only performed for each luminaire 4, rather than each individual lamp 12, wherein the commissioning involved in reporting the identifiers of the slave lamps 12b-12d to the commissioning tool 6 and joining these slave lamps to the network is performed completely "behind the scenes".

An exemplary workflow for the case where all TLED tubes 12a-d within luminaire 4 are newly installed before the automatic grouping starts, namely Factory New (FN), is described below. This is illustrated by way of example for a room with N luminaires 4, where each luminaire has four TLED tubes 12a-12d, which are commissioned into a ZigBee network. In the following description of the lamp 12 performing an operation, it may be assumed that this is performed using the respective wireless interface 28, as appropriate, under the control of its respective controller 26.

First, four times as many as N Factory New (FN) TLED tubes 12 are inserted into N luminaire fixtures 4, respectively. Initially, each FN TLED 12 detects that there is no ZigBee network (or only one or more networks with a reception strength below a threshold, which can be assumed to have to come from another luminaire or even another room, see the "bucketing" feature described later).

Each TLED 12 in the environment 2 then starts to start a new ZigBee network in FN mode (note that no bridge or remote control commissioning device 6 needs to be present within the system at that time). This means that: each lamp 12 in the environment 2 transmits a transmit beacon which communicates the fact that it is a new lamp searching for neighbors. These beacons include a unique identifier number (e.g. the 64-bit ZigBee address of the TLED). All TLEDs 12 also listen to these beacons and analyze the addresses of the other TLEDs with respect to their own address. The single TLED 12a with the lowest address initiates the second phase of auto-commissioning by modulating its 64-bit ZigBee address onto the ballast line connecting it to the ballast 10, by modulating the load it places on the ballast (discussed in more detail later). All other TLEDs 12 check if the power they receive from ballast 10 is being modulated. If so, these TLEDs 12b-d each grab (grab) the 64-bit address they have received via ballast load modulation. This 64-bit address is the ZigBee address of the master TLED 12a in its own luminaire 4. Note that: the lamps 12 are not all turned on at exactly the same time and the process is started. Legally, the power of the luminaire 4 should be off during relamping, so that if this rule is complied with, the lamps will all be switched on together after relamping and thus the process starts at the same time. In practice this rule is not always adhered to, but nevertheless the described process will still work as long as the lamps 4 are configured to continue searching for potential master or slave lamps for some limited window after being powered up.

An alternative for selecting the main lamp would be to use a random timeout after powering up the mains (mains)16, before each TLED 12 is allowed to start its radio 28. The radio 28 on which the first active TLED 12 becomes the master TLED and starts the network. The random timeout feature of the TLED tube 12 is disabled after a certain period of time, for example one month, if the TLED 12 is still not debugged. However, this random timeout scheme is not preferred: this process takes time and, in addition, it is difficult to size (dimension) for both small and large networks (the larger the network, the longer the required startup delay). However, load modulation works directly and for any network size.

Regardless of the method used to pick the master and slave, each of the slave TLEDs 12b-d then joins the ZigBee network of the ZigBee master TLED device 12a (causing each of these slave devices to switch to non-FN mode and stop beaconing). The master TLED 12a notes: one or more TLEDs 12b-d have joined their network. This network is used by master 12a to obtain unique numbers (e.g. 6 digit remote reset codes) from its slaves 12b-d, where these are later used during the commissioning process to pull slave TLEDs 12b-d into the ZigBee network established by the installer remote (commissioning tool) 6.

After having determined which of the TLEDs 12 are located within the same luminaire 4, the master TLED 12a saves the unique addresses of its slave TLED neighbors 12b-12d together with network parameters and keys. The master TLED 12a exits the network it created for its slaves 12b-d and goes back to FN mode to appear to the commissioning tool 6 as waiting for commissioning. However, it leaves it in this newly created network from the TLEDs 12b-d so that they do not appear to the commissioning tool 6. Thus, master 12a serves as its representative of slaves 12 b-d.

Since the master 12a has returned to the FN mode, this means: it will start the originating beacon again. To avoid considering this in the distributed protocol for selecting the next master, it is therefore indicated in one or more of its beacons: it has acted as the master.

Generally, in terms of signaling, TLED 12 needs a mechanism to communicate some unique ID, its presence and whether they have been grouped according to illuminator 4. A normal ZigBee beacon contains, inter alia, an extended PAN ID of its network, but does not provide space or a mechanism to include other information that the TLED 12 may need to exchange. Thus, one of the following alternatives may be used to indicate whether the master 12a returning to FN mode is already a master (grouped with the lamps 12b-12d in its respective luminaire).

A first possibility is to use a privately defined advertisement message over ZigBee. According to this scheme, each lamp 12 starts its own ZigBee network and is not open for other devices to join that network. At one or more times (as initial beacons and/or later) throughout the commissioning process, each TLED 12 periodically (at some predefined interval) sends an inter-PAN advertisement message on its own network containing information relevant for the present purpose (e.g. MAC address, indication of being master-slave TLED within the luminaire, whether automatic grouping with slave TLEDs in the luminaire has occurred). For the remaining time it listens on either its own channel or all channels (see comments below) for similar messages from other TLEDs 12. Each factory new TLED listens to all such messages within its radio range and acts accordingly (see rest of the text). If the TLED 12 has performed automatic grouping, it adjusts the content of its advertisement messages accordingly. After debugging is complete, sending the advertisement message may continue for use cases such as replacing one of the TLEDs (discussed in more detail later).

The above can be performed with all TLEDs 12 on all their known ZigBee channels (as it is easiest for a device to listen on only one channel) or each TLED can pick on a random ZigBee channel (which means that each device needs to listen on all channels, with slightly more involvement, but allows good propagation on all ZigBee channels).

A second possibility is to use modified beacons. This is similar to the first possibility above, rather than the announcement message using beacons as defined in the ZigBee specification, the protocol bytes are set to a different value than for the existing system (00 = ZigBee Pro, etc.). In the payload, various information (the same as described for the first possibility above) is carried.

A third possibility is to use an alternative type of beacon other than ZigBee beacons of another protocol than ZigBee. This is a variant of the first and second possibilities above, but the information in question is transmitted in alternative beacons, such as ble (bluetooth Low energy) iBeacon.

Whatever the way the first master 12a indicates that it has become the master, the other TLEDs 12 in the other luminaires 4 that have not been automatically grouped note: in case this indication is not given, they no longer receive beacons from the master TLED 12a in the first luminaire. This means that: the other TLED 12 will now have the lowest unique number, assign itself the primary role for its luminaire 4, and repeat the above process for this luminaire. The whole process is repeated until the respective master TLED 12 in each luminaire 4 has completed these steps.

Note that: optionally, the process flow described above may be enhanced by using measurements of the received signal strength of the beacons, e.g. Received Signal Strength Indicator (RSSI), to assist in the selection of the pipe neighbors 12b-12d within the luminaire 4 by detecting pipe neighbors with sufficiently high signal strength. That is, RSSI can be used to speed up the TLED auto-commissioning process. Beacons with RSSI below a predetermined threshold can be ignored so that multiple luminaires 4 (e.g. in a large open office) can run the above automatic grouping process simultaneously, independently verifying which TLEDs 12 are indeed located within the same luminaire 4. The RSSI alone is not necessarily reliable enough to identify TLEDs 12 residing within the same luminaire 4 with sufficient certainty. Thus, in an embodiment, the RSSI is only used to create RSSI-based buckets (i.e. candidate subsets) of TLEDs 12, e.g. those TLEDs that are likely to be within the same luminaire, or those TLEDs that are likely to be within the same luminaire. Based on these buckets, a second identification mechanism is then used, e.g. to short the electrical load of one master TLED 12a and to detect ballast load changes on another slave TLED 12b-d within the luminaire, in order to more reliably determine which TLEDs 12 are indeed positioned within the same luminaire 4.

In the next phase of the commissioning procedure, the installation user (person) 8 participates in the commissioning. The installation user 8 sees on his commissioning tool 6 that only one FN lamp 12 per luminaire 4 is displayed (i.e. master TLED). If the user 8 wishes to include the luminaire 4 of one of these visible FN lamps 12a in the network he or she is creating, he or she selects that lamp 12a in the user interface of the commissioning tool 6. This causes the commissioning tool 6 to send a commissioning request to the selected lamp 12 a. In response, this light 12a provides a visual indication to the user 8, for example by flashing its light emitting element 18. The user 8 is thus able to see: the lamp 12a he or she chooses is indeed in the luminaire 4 he or she intends to commission. If so, the user confirms this via the user interface of the commissioning tool 6, causing the commissioning tool 6 to include the master TLED in its ZigBee network (i.e. create a wider ZigBee network for the purpose of controlling the lamps 12 in subsequent phases of operation). The master TLED 12a also tells the commissioning tool 6 about its three non-FN TLED slave devices 12b-d (including its unique ID, e.g. ZigBee address). The slave TLEDs 12b-d then join the ZigBee network established with the commissioning tool (or lighting bridge). There are at least three options for this.

The first option is: for the commissioning tool 6, using the unique ID of the slave TLED will be pulled from the lamps 12b-d into its network using the 6-digit reset code. These can be broadcast by the commissioning tool 6 so that the slave TLEDs 12b-d become FN again and join the commissioning tool's remote network.

As a second option, the master TLED 12a temporarily returns to the old network (the network it created with its slaves 12 b-d) and uses this to transmit to its slave TLEDs 12b-d the parameters of the new network (the network created with the commissioning tool 6). The slave TLED tubes 12b-d then switch to the new network and the master TLED tube 12a also returns to the new network of the commissioning tool 6.

In a third option, the commissioning tool 6 instructs the master TLED 12a to send a "remote reset" to its slave TLEDs 12 b-d. The master TLED 12a temporarily returns to the old network and transmits a "remote reset" to its slave TLEDs 12b-d, causing the slave TLEDs 12b-d to become FN again. The master TLED tube 12a then goes back to the network of commissioning tools 6. The commissioning tool 6 searches for a new device and finds three slave TLEDs 12 b-d.

Thus, the master and slave lamps 12a-d are all pulled together into a wireless network (e.g. a ZigBee network) created with the commissioning tool 6, so that these lamps 12a-12 can then be controlled via that network in the operational phase. Whatever the option used, the commissioning tool 6 preferably also assigns a group address (e.g. a ZigBee group address) to the lamps 12a-12d in the same luminaire 4 (each respective luminaire is assigned a different respective group address). This group address then allows a control device (not shown) to control the lamps 12a-d together by broadcasting one or more control messages, each control message having only a single group address as a destination address (instead of transmitting a separate message to the individual address of each lamp). For example, according to ZigBee, a message can be broadcast together with a group identifier, whereby only the lamps 12 containing this identifier (i.e. in this group) will react. When assigned, the commissioning tool 6 communicates the group address to the master 12a and each slave light. In operation, each lamp 12a-12d then listens for all messages with that group address and reacts accordingly. However, note that: it is not necessarily required to have a group address for all TLEDs within a luminaire. Alternatively, it is possible to simply address each TLED with its own individual address once the debugging process is over.

Thus the above describes a mechanism that can be used to commission the arrangement of newly installed luminaires 4. Further scenarios in which automatic grouping may be used are: when one of the individual TLEDs 12 in a given luminaire 4 is replaced, at a later time after the initial commissioning phase has ended and the operational phase has started. The following describes an alternative workflow for one of the non-FN TLED tubes 12 in the illuminator 4. The goal of this connected TLED field replacement is "out-of-box" auto-commissioning of the replacement TLED 12 without involving remote control or commissioning experts. The automatic grouping process can be triggered once via the switch by a combination of factory new connection TLED tubes 12 and power-cycling of the mains voltage 16. Alternatively, the relamping person may actively trigger an automatic commissioning for the replacement tube (e.g., 5 mains switch toggles within 10 seconds).

The automatic commissioning of the replacement TLED proceeds as follows. A newly installed TLED, for example, a replacement for 12b, sends a signal to ballast 10 by modulating the load it places on ballast 10. The other TLEDs 12a, 12c, 12d in the same luminaire 4 hear this message in the power supplied to them by the ballast 10. One of these TLEDs 12a, 12c, 12d opens its network (e.g. the TLED with the lowest unique address, or the TLED 12a that has become the master of the luminaire 4). The new TLED then joins the network. The master TLED 12a programs the appropriate ZigBee group in the new TLED so it functions in the same way as the replaced TLED 12 b.

This assumes that: the commissioning tool 6 has allocated all TLEDs 12a-d in the luminaire 4 to a single ZigBee group. Having all TLEDs 12a-d within a luminaire 4 in the same group is very advantageous for this replacement use case, since the ZigBee group number of the remaining old TLEDs 12a, 12c, 12d can then be directly reused for the new replacement TLED. Unlike ZigBee group addresses, normal ZigBee addresses do not have this feature: the new replacement TLED will always have a different 16-bit address than the old one.

The above mechanism may include a timeout when no one answers the request. Or alternatively the new TLED may send a request for the network over ZigBee, which is monitored and answered by the other TLED(s) 12a, 12c, 12d or at least the master 12a of the luminaire 4. Also here, the signaling via the ballast line can (and preferably is) used to verify that both are within the same luminaire 4. For TLED field replacement, this verification that a "wild" wireless node that wants to join the lighting network is indeed connected to the fluorescent tube ballast 10 also serves as a security mechanism, which can only join if it is physically located in the same luminaire 4 as the existing member 12a of the network, thus avoiding rogue devices from joining for malicious purposes such as attempting to destroy the lighting. Sharing the same fluorescent tube ballast 10 is a TLED market that employs several ways similar to the touch link mechanism for consumer applications. In consumer applications, the pairing procedure requires remote control of physical proximity to the light bulb to prevent malicious pairing of new network components with, for example, a light from outside the enclosure 14. In the same way, embodiments of the present disclosure enable an existing lamp 12a to assess the authorization of a new ZigBee component to join the network by verifying that the new wireless component purporting to be a TLED is indeed wired on the same ballast 10 as the existing connection TLED 12a and is therefore indeed a replacement TLED rather than another malicious wireless device.

Summarizing the above, fig. 9 presents a state diagram showing different possible states of the lamp 12 according to an embodiment of the present disclosure. Each lamp begins its life (start life) when first powered up in an "out-of-box" state 54 in which it executes a distributed negotiation protocol to determine whether to become a master or slave, as discussed above. Based thereon, one of the lamps 12a then transitions to the master state 56, while the other lamps in the same luminaire all transition to the slave state 58. When the first lamp 12a is in the master state 56 and the second lamps 12b-d are in the slave state 58, the master lamp 12a interacts with the commissioning tool on behalf of the first and second lamps 12a-d together to initiate one or more steps to commission those lamps 12a-d as a group. Finally, after commissioning is finished, both the master and slave lamps 12a-12d transition to an operational state (operational phase) 60 in which they are available for their final purpose, i.e. are used to illuminate the environment 2, and are controlled (e.g. dimmed, used to set a colored lighting scene, etc.) via a ZigBee network or other such wireless network established with commissioning tools. In the operating state 60, each lamp 12 monitors for a signal to a potential replacement lamp, as discussed above.

Note that: whether (a) the lamp is in FN ("Factory New") mode is a separate variable than whether (b) it is in "out-of-box", master, slave, or in the last operating state. This can be seen by considering the following: when a lamp is a master it switches between FN and non-FN, and also when a lamp is a slave it can switch between FN and non-FN, so (a) and (b) are individually controllable factors. Thus, the technique disclosed herein involves intentional and human manipulation of the FN state such that it not only indicates whether or not it is newly "out of box" but is also used for the additional purpose of controlling which lamps among the plurality of lamps 12 in the same luminaire 4 appear to the commissioning tool 6.

Constrained signaling channel

The use of load debugging via signaling via the ballast may be particularly advantageous compared to automatic grouping based on RSSI only. For example, in the USA, the luminaire always has a continuous metal housing for the upper top and sidewalls of the luminaire 4. The metal sidewalls of the luminaires block the direct wireless path (in the same plane) between TLEDs 12 positioned in different luminaires 4. As a result, the wireless attenuation between TLEDs 12 positioned in two different luminaires 4 is typically stronger than the wireless attenuation of two adjacent TLEDs positioned within the same luminaire 4 over a distance of 15-20cm (centimeters). However, in order to be smaller than the usual mounting distance between adjacent luminaires 4, the attenuation caused by the luminaire metal sidewalls will in some cases be insufficient to prevent accidental automatic grouping of connected TLED tubes 12 from different luminaires (e.g. if the punch holes in the luminaire metal sidewalls are located right beside the TLED's radio 28). Additionally, each of the TLED tubes 12 may have its radio 28 located in only one end cap 20i of the tube 12. Thus, the following will have a 50% likelihood: two adjacent TLED tubes 12a, 12b located within the same luminaire 4 will be installed by the installer with radios 28 on opposite ends of the tubes 12. Placing the antenna 28 in the middle of the TLED may overcome this problem. However, from the perspective of the TLED hardware, the preferred radio location in the connection TLED is within the end cap 20.

To ensure sufficient robustness, it is therefore preferred to "bucket" the TLEDs 12 with the help of RSSI, and then use the second packet method to determine unambiguously which TLEDs 12 are located within the same luminaire 4.

For the second automatic grouping method, there are at least two options. As mentioned above, one embodiment is: the master TLED 12a tube signals (e.g., signals its unique ID) via the ballast 10 by modulating the load it places on the ballast 10. The other TLEDs 12b-d then look to detect load transitions caused by their sister TLEDs within the same luminaire 4. This will be discussed in more detail later.

However, as an alternative embodiment, each of the connection TLEDs 12 may have an integrated light sensor that can be used to allow the slave 12b-d to detect the light modulation pattern emitted by the master TLED 12a (and/or the slave 12b-d can emit the light pattern to be detected by the master 12 a) located within the same illuminator 4. The light sensor may be a pre-existing daylight sensor or a dedicated light detector for the disclosed detection purposes. Master 12a will selectively turn off the light within luminaire 4 to help the master TLED tube receive the coded light message from its neighbors 12b-d without interference from its own light. The coded light can be used to detect which lamps 12 are within the same luminaire, since the housing 14 of the luminaire 4 serves to at least partially block the coded light signals, so that the lamps 12a-d in the same luminaire 4 will receive signals from each other, but not from the lamps 12 in the other luminaires 4. To facilitate this, the light sensors and/or the positions of the lamps 12 may be arranged specifically such that only the light sensor of a given lamp 12 in a given luminaire 4 or at least mainly receives light from lamps in the same luminaire 4. For example, the light sensors may be arranged to face upward to detect light reflected from an upper reflective element in the interior of the respective luminaire housing 14. A similar principle can even be applied using other media as means for detecting whether the lamp 12 is in the same luminaire: for example, each lamp 12 may emit an ultrasonic signal that is blocked by the housing 14, or each lamp 12 may emit a radio signal that is blocked by metal elements around the luminaire housing 14 (so that signals can be received from the controller or commissioning tool 6 below the luminaire 4 rather than from other luminaires mounted on the same ceiling).

As an additional feature, in an embodiment, by using a light sensor of each TLED 12, it is possible to identify the relative positioning of the TLED tubes 12a-d within the illuminator 4. This enables directional illumination scanning (sweep) (left to right, or right to left) across the four TLEDs 12a-d within the luminaire 4. This dynamic rotation of the light beam may make it possible to identify the directivity between adjacent luminaires 4, which may enable automatic commissioning at room level. In this solution, TLEDs 12 arranged within the same luminaire 4 switch their light on sequentially from the left to the right side of the luminaire. At the same time, the LEDs of the TLEDs in adjacent luminaires remain switched off, but the light lux level on the floor caused during sequential switching on of the TLED tubes within adjacent luminaires is detected with the light sensing means. The closer the lit (light-up) TLED tube is physically to the receiving TLED, the more light will be on the floor. Based on the detected lux levels on the floor during the stepwise switching of these tubes, the TLED tube (in off mode) can deduce whether the adjacent luminaire performing the scanning light is actually located to its right or to its left.

An exemplary implementation of a technique for intentionally modulating the load placed on ballast 10 by master 12a in order to signal the pattern in the power supplied by ballast 10 to lamps 12a-d in the same luminaire 4 is now described below.

As discussed, the fluorescent luminaire 4 typically takes several TL-tubes 12a-d wired to one single ballast 10. A typical wiring diagram for an Instant Start (IS) ballast 10 IS shown in fig. 4. At each end of the TL tube 12, two pins 22 are shorted by a shunt socket. Pins 22a, i on one end of a first lamp 12a in the luminaire 4 are connected to the ballast 10 via a first blue line 30a, while pins 22b, i on one end of a second lamp 12b are connected to the ballast 10 via a second blue line 30a (and so on, if there are more than two lamps in the luminaire). On the other end, pins 22a, ii and 22b, ii (etc.) are all connected together and to ballast 10 via the same red wire 32. The ballast 10 itself is connected to the mains 16 via a black line 34 and a white line 36.

Fig. 5 and 6 show examples of different types of ballasts 10 for powering fluorescent tubes. By way of example, these are the dominant topologies in the NAM region for Instant Start (IS) ballasts, i.e., self-oscillating (SO) circuits (see fig. 5) and current-fed half-bridge resonant circuits (see fig. 6).

Figure 5 shows a typical High Frequency (HF) fluorescent ballast. This ballast 10 includes an EMI (electromagnetic interference) filter 38 arranged to receive the upstream mains power supply 16 and filter this to produce a filtered power supply and block interference generated by the ballast back to the mains. Ballast 10 also includes a PFC (power factor correction) input stage 40 connected to receive filtered power from EMI filter 38 and to perform power factor correction on the filtered power to produce a power factor corrected power. The circuit further comprises a resonant output stage 42 connected to receive the power factor corrected power supply from the power factor correction stage 40. This circuit operates in a self-oscillating mode to generate a final power supply for powering the fluorescent tube (or its TLED replacement 12) based on the received power factor corrected power supply. The two transistors in the resonant circuit 42 are driven with the auxiliary winding of the transformer T1. The output is typically isolated from the mains 16. The ballast 10 thus generates an HF voltage of approximately 600V (volts) across the secondary winding of T1. Capacitors C1 and C2 are connected in series with each of the lamps 12a, 12b, respectively. The capacitors C1, C2 act as ballast elements and control the lamp current.

Among the latest products, half-bridge (HB) resonant circuits have become more popular due to their cost savings. A typical HB fluorescent ballast topology is shown in fig. 6. This circuit is similar to that of fig. 5, but the SO resonant circuit 42 is replaced by an HB circuit 44. The HB circuitry 44 is typically controlled using an Integrated Circuit (IC). The output is not isolated from the trunk 16.

Details of some exemplary techniques for transmitting and receiving signals via a ballast 10 such as that shown in fig. 5 and 6 or otherwise will now be described in more detail with reference to fig. 7.

Fig. 7 shows an example lamp 12 for performing load modulation for signal transmission via ballast 10, and also detecting such signals from other lamps 12 via power received from ballast 10. In an embodiment, each lamp 12 in one, some or all of the luminaires 4 may be configured according to fig. 7.

As shown in fig. 7, the lamp 12 comprises a rectifier 23 comprising an arrangement of diodes D1, D2, D3, D4 arranged to receive AC power from the ballast 10 via pins 22 of the lamp 12 and convert this to DC power. Various forms of rectifiers are known per se to those skilled in the art and the rectifier 23 does not necessarily have to take the form shown in figure 7 (although this may work well). The lamp 12 further comprises an LED driver 24 arranged to receive the DC power from the rectifier 23 and based thereon generate a constant or approximately constant current to the LED-based lighting element 18 (LED string or array). However, note that: constant current as referred to herein does not necessarily mean: the current is not adjustable. Instead, the lamp 24 comprises a controller 26, for example comprising a microcontroller 46 arranged to execute embedded firmware of the lamp 12. Further, the lamp 12 comprises a wireless interface 28, such as a ZigBee, Wi-Fi, 802.15.4 or Bluetooth interface (described above primarily in terms of the ZigBee example). The microcontroller 46 is connected to the wireless interface 28 and the LED driver 24. It is arranged to receive messages, e.g. originating from a lighting controller or one or more wireless sensors (not shown), via the wireless interface 28 and to determine a light output level to be used by the light-emitting elements 18 for emitting light based thereon. The microcontroller 46 then indicates this light output level to the LED driver 24 and, in response, the LED driver 24 sets the current to the appropriate level to achieve the desired light output. The current supplied by the LED driver 24 is therefore constant, because: for a given light output as indicated by the controller 26, the LED driver 24 ensures that the current is approximately constant. Also, note that: in the case where Pulse Width Modulation (PWM) dimming or the like is used, the constant current refers to an average current. Further, in embodiments, the LED-based lighting element 28 may comprise different color, independently controllable LEDs or sub-arrays of LEDs. In this case, the controller 26 and the LED driver 24 may also individually set the output level of each different color LED or sub-array in order to control the color of the light output.

For signal transmission via the ballast 10, the internal controller 26 of the lamp 12 further comprises a transmitting circuit in the form of a transistor switch M1, which is connected so as to be able to modulate the load placed on the ballast 10 by the respective lamp 12 under the control of the microcontroller 46. In the example embodiment shown, this is done by connecting the source and drain (or collector and emitter) of transistor M1 in parallel across the load, e.g., across the LED driver 24 or light emitting element 18, and the gate (or base) of transistor M1 connected to the controller 26. This allows the controller 26 to selectively short circuit the load by controlling the gate (or base) of transistor M1. When it does so, this causes "hiccup" to be fed back through the ballast 10, which is detectable in the power received by other lamps 12 in the same luminaire 4. By controlling the short-circuit according to a suitable predetermined code (see below), it is thus possible to signal other lamps 12 in the same luminaire 4 via the ballast 10.

To be able to sense such signals from other similar lamps 12 in the same luminaire 4, the lamp 12 of fig. 7 further comprises a sensing circuit 50 connected between the rectifier 23 and the LED driver 24 (although it could potentially be connected in other parts of the circuit). This circuit 50 is configured to detect a pattern of signal transmissions that "hiccup" in the power supplied by the ballast 10, and supply the detected signals to the controller 26 for decoding. The sensing circuit 50 may be configured to sense the modulation in the received power by sensing the modulation in the current, voltage, and/or frequency of the received power. For example, in an embodiment, the sensing circuit 50 is a current sensing circuit.

Thus, the controller 26 is able to transmit signals via the ballast 10 and also act on such signals according to the various commissioning procedure steps disclosed herein in order to perform automatic grouping of the lamps 12a-d in the same luminaire 4.

To start the TLED grouping method, one master TLED lamp 12a (e.g. from a bucket of TLEDs that may share the same luminaire 4) starts the automatic grouping process. During the automatic grouping process, this master TLED lamp 12a begins the LED load shunting process and opens and closes switch M1 at a predefined frequency and duty cycle (as determined by microcontroller 46). A change in lamp current is sensed from each of the TLED lamps 12b-d via its internal current detection unit 50. When the master TLED lamp 12a performs this code-splitting action, the loading condition of the ballast 10 changes and the ballast deviates from its normal operating point. As a result, the remaining TLED lamps 12b-d in the group receive more or less power from the ballast 10. The magnitude and direction of the change depends on the fluorescent ballast topology, but in any case the change will be noticeable from the TLEDs 12 b-d. This change is sensed from the TLED lamp with a detection unit 50 within the lamp. Since the ballast 10 is a current source, the code shorting performed by the master TLED 12a lamp is a safety action and will not damage either the ballast 10 or the TLED lamps 12 a-d.

The load shorting function can be implemented within the TLED 12 at low cost, for example, using a shunt switch M1 as shown in fig. 7. In each TLED 12, this instance of shunt switch M1 is placed after the rectifier 23 (this switch M1 may in fact already be present in the existing TLED 12 for pulse width modulation dimming purposes). When M1 is off, the lamp input is shorted and current from ballast 10 is bypassed without delivering power to LED load 18. To detect the codes transmitted by the other TLEDs 12, an instance of a current detection block 50 is inserted in the main current loop of each TLED lamp 12. Coded changes in ballast current and frequency are sensed via this detection block 50 and the extracted signal is fed to the on-board microcontroller 46 within the TLED 12. The same microcontroller 26 also controls the shunt switch M1.

Note that: in an embodiment, filament circuits 52i, 52ii may be included on the inputs 22i, 22ii on both sides of the TLED 12, respectively, in order to mimic the filaments of a real fluorescent tube lamp. This circuit 52 may be, for example, a power resistor, or may remain on for an instant start ballast. The filament circuit 52 will therefore pass the code of the signal transmission without any effect on the signal.

Fig. 8 illustrates an example shape in the time domain t (after conditioning) of the ballast current I received from the lamps 12b-d according to embodiments disclosed herein. The top sketch (sketch) shows the current during normal operation, whereby the ballast current received from the TLEDs 12a-d is at a steady level. The master TLED lamp 12a then starts with a grouping process and imposes a coded pattern on the ballast 10. As a result, as illustrated in the bottom sketch of fig. 8, the current received from the TLEDs 12b-d contains a modulated signal pattern with a frequency equal to the shunt frequency of the main lamp. The shunt frequency can be, for example, in the range of 1-10Hz or in the range of several hundred Hz to several kHz (preferably the mains frequency is avoided to minimize unnecessary interference due to mains frequency components).

There are several ways for the current detection unit 50 to detect the coded modulation pattern. In a first option, the detection is done by sensing a change in the average current value. First, the sensed signal is averaged via a low pass filter. This value is then read by the microcontroller 46 and compared to the nominal value. The microcontroller 46 then decides whether this represents a signal from another lamp 12 that shares the common ballast 10 with its own respective lamp 12. For example, each slave lamp 12b-d may listen on ballast 10 for a signal from master lamp 12a identifying the master lamp, and if slave lamp 12b-d detects this, the respective slave lamp 12b-d replies to master lamp 12a via wireless interface 28 to inform master lamp 12a of the slave lamp's identity (e.g., address). Or vice versa, the master lamp 12a may listen on the ballast 10 for signals received from the slave lamps 12b-d identifying themselves to the master lamp 12a by the ballast 10.

As a second, alternative or additional option for detection, the detection may be done by measuring the frequency of the received modulation. The master TLED lamp 12a can even send some basic messages to the slave lamps 12b-d by modulating the frequency, duty cycle etc., if required. This second option is more accurate than the first option above, since different ballast circuit topologies result in different modulation depths of the TLED current. The average detection method used by the first option is therefore more error prone (although not necessarily so) than the second option.

In view of the encoding schemes disclosed above for signaling information via ballast load modification schemes, various encoding schemes are possible. For example, the ballast-based communication channel between the master and slave TLEDs 12a-d may utilize a binary encoding scheme, such as Morse code, Manchester code, or pulse position modulation, among others. The signaled information may include the 64-bit unique ZigBee address (or other unique identifier) of some or all of the transmitting lights, optionally along with some other bits such as header bits, start and stop bits, and/or possible error detection or correction bits. In some embodiments, this communication channel may also allow additional information to be transmitted, for example, via the addition of bytes of "opcode". The slave lights 12b-d may be enabled to confirm to the master lights 12b-d that: either via the ballast 10 or via the wireless interface 28, which have received the signal. After signaling, main light 12 returns to FN mode and engages with commissioning tool 6 (engage), as previously discussed.

Note that: signaling on the ballast 10 can also be accomplished via modulation of only a portion of the brightness range of the LEDs 18 (e.g., between 100% and 80% light output) instead of the full 100% to 0% (off lamp) modulation. Similar to the coded light type coding, this 100% -80% modulation can even be utilized later in the operational phase for "side channel" based on ballast load variations, which is not visible to the end user during normal lighting operation.

After the automatic grouping is completed, both the master and slave TLED lamps 12a-d cannot be controlled until they have been commissioned by the installer 8. There are several options as to which light levels are to be picked during the state in which the TLEDs 12a-d are automatically grouped but have not yet been debugged. In one embodiment, master light 12a and slave lights 12b-d are automatically set at different light levels to enable a quick visual check for (first) installer 8 as to whether the automatic pairing is properly completed.

Further examples of the invention

It will be appreciated that: the above embodiments have been described by way of example only.

For example, while described above in terms of the microcontroller 46 in each lamp 12 performing various respective functions, it will be appreciated that: any software or hardware implementation of the controller 46 can be used to achieve the same functionality. For example, the described functionality of the microcontroller 46 may instead be implemented in software running on multiple processors or in dedicated hardware circuits or in configurable or reconfigurable circuits such as PGAs or FPGAs.

Further, the debugging procedure disclosed above can also be used with other protocols than just ZigBee or ZigBee Light Link. At its most root, the factory new mode is a mode in which the lamp 12 appears new, i.e. to be waiting for commissioning, to the commissioning tool 6, whereas the non-factory new mode is a mode in which the lamp 12 does not appear new to the commissioning tool. Other protocols may have to or may be modified to incorporate a similar pairing pattern and could also benefit by using a human-operated factory new pattern (or the like) to collectively represent the lamps 12a-d in the same luminaire 4 as part of the commissioning process.

Further, in the above, it has been described that: the main lamp 12a detects the other lamps 12b-12d in the same luminaire 4 by signalling on the ballast 10 and subsequently receiving back via another medium in the form of a wireless network (e.g. a ZigBee network) the identifiers of those other lamps. Alternatively, however, the slave lamps 12b-d could instead respond via the ballast 10 (e.g., each randomly sending its response, or using carrier sense multiple access techniques). Or as another alternative, the slave lamps 12b-d can initially transmit their identity signals to the master lamp via the ballast 10 (without first waiting for a signal from the master lamp). Also, the protocol for determining which lamp will become the master lamp can be implemented via other means than just radio beacons; for example via the ballast 10 or via coded light or ultrasound. Furthermore, alternative protocols for selecting the main lamp can be used: for example, the main lamp is not necessarily the lamp with the lowest address, but can instead be the lamp with the highest address or an address (or more generally an ID) selected according to some other rule. Alternatively, the selection need not even be based on an address or identifier, and can instead be based on some other attribute in the beacon, such as a separate priority indicator in each beacon (so that the light with the highest priority level becomes the master light).

Further, the commissioning procedure is not limited to grouping lamps 12a-d in the same luminaire 4. More generally, the disclosed commissioning procedure can also be used with other ways of determining the lamps 12 to be grouped, not just based on detecting whether in the same luminaire 4. For example, other reasons for grouping lights can include grouping clusters or regions of lights within a room. In such a case, it is possible to arrange the lamps 12 to each emit a signal comprising an identifier of the respective lamp 12, such as a coded light signal, a radio signal or an ultrasonic signal (without that signal necessarily being obstructed by the respective housing 14); and each lamp 12 is arranged to also listen for signals from other lamps in its neighbours in order to measure received signal strength (e.g. RSSI) or time of flight (ToF). By collecting these measurements together (either on the main one among the lamps 12 or on a central device such as the commissioning tool 6 or lighting bridge), it is possible to detect the relative distance between the different lamps 12 and thus to deduce the topology of the lamps 12 in the environment 2 in order to detect which lamps will be considered to be in the same cluster.

Conversely, the disclosed techniques for detecting whether a lamp is in the same luminaire may be used with other commissioning procedures, without necessarily involving factory new modes or such manipulations, or indeed in any other situation it may be desirable to detect: the lamps are in the same luminaire 4 (e.g. for auditing purposes, or for being controlled as a group in a particular way without a specific commissioning phase).

Further, there are other possibilities for modulating the load, in addition to the on/off (in/out) scheme shown in fig. 7, whereby the switch M1 is used to switch the load between either zero or full load. For example, alternatively, the LED 18 and/or driver 24 may remain connected in circuit and not fully shorted, but may include a switchable or variable resistance or impedance in series or parallel with the LED 18 and/or driver 24, and the microcontroller 46 may control this switchable or variable resistance or impedance to modulate the load. Or more generally, other power line communication techniques may be available to those skilled in the art. Furthermore, the disclosed techniques for modulating power may be applied not only in the context of ballast 10, but also in any other power supply circuit, such as a circuit including a transformer.

Note also that: for the avoidance of doubt, the term "wireless light" or the like as used herein refers to the fact that: the lamp is able to communicate wirelessly, rather than it requiring a plug-in power supply. In general, the wireless lamp may be powered by any means, such as mains power or by a battery, for example, the TLED tube may be powered by an emergency lighting battery positioned within the luminaire.

Further, the term beacon in this application is not limited to a ZigBee beacon, and can also be any message repeatedly sent out with a lamp, e.g. a message looking for an open network (or any message exposing an open network). Another alternative is: the device will or will not respond to the offer to open the network depending on its master/slave status. In this case, the lamps only listen and do not themselves transmit beacons. Conversely, if the commissioning tool sends an offer to open the network, the master device will react to the offer and the slave device will ignore it.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that: a combination of these measures cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems. Any reference signs in the claims shall not be construed as limiting the scope.

Claims (14)

1. A first lamp for use with one or more other lamps in a multi-lamp luminaire, each lamp being operable to emit a respective illumination embedded with a predetermined coded light message;

wherein the first lamp comprises:

one or more light emitting elements for emitting respective illumination intensities;

a local controller;

a communication interface configured to enable the local controller to communicate with a corresponding controller on each of one or more other lamps in the multi-lamp luminaire, the communication comprising sending and/or receiving one or more signals; and

a coded light emitter operable to modulate a coded light message into a respective illuminance of a first light;

wherein the local controller is configured to: coordinating with corresponding controllers of one or more other lamps based on communication via the communication interface to prevent unsynchronized instances of the coded light message from being transmitted from different ones of the lamps in the multi-lamp luminaire, the local controller being configured such that the coordinating comprises any of:

a) coordinated so that each of the first lamp and one or more other lamps transmits a respective instance of the same coded light message and all instances of the message are synchronized to begin transmitting at the same time, or

b) Coordinating such that only one lamp among the lamps in the multi-lamp luminaire transmits a message and none of the other lamps among the lamps in the multi-lamp luminaire transmits any coded light, such that if a first lamp is to transmit said message, the local controller selects to operate the first lamp in a coded light transmission mode in which the coded light emitter transmits said message, and if one of the other lamps is to transmit the message, the local controller selects to operate the first lamp in a non-coded light transmission mode in which the first lamp does not transmit said message.

2. The first lamp of claim 1, comprising a mechanical connector for connecting to a complementary connector of a multi-lamp luminaire to connect the one or more light-emitting elements to a power circuit of the multi-lamp luminaire to power the one or more light-emitting elements to emit respective illumination intensities.

3. The first lamp of claim 2, wherein the local controller is configured to perform the coordination by a); and wherein the first lamp further comprises a timing circuit configured to use the periodic variation of the voltage and/or current of the power supplied by the power supply circuit in order to derive a clock signal common to the first lamp and the one or more other lamps,

wherein the coded light emitter is configured to synchronize the start of the respective instance of the coded light message to the clock signal, thereby synchronizing the start of the respective message to the start of the message transmitted by the one or more other lamps.

4. The first lamp of claim 3, wherein the timing circuit comprises a frequency divider, wherein the coded light emitter is configured to derive the clock via the frequency divider such that the clock signal has a frequency that is lower than the periodic variation of the power supply.

5. The first lamp of claim 1, wherein:

the local controller is configured to perform the coordination by b);

the local controller is configured to select between operating the first lamp in a plurality of different sub-states of the coded light transmission mode, each sub-state modulating the message into a respective illumination with a different modulation depth; and

the local controller is further configured to: detecting what number of other lamps are present in the multi-lamp luminaire based on the communication via the communication interface, and selecting between different sub-states depending on the detected number.

6. The first lamp of claim 5, wherein the local controller is configured to receive a dimming signal indicating that the first lamp and the one or more other lamps adjust the intensity of their respective illumination upward or downward; and

wherein the local controller is further configured to, in response to the dimming signal: the respective illumination emitted from the first lamp is adjusted with a smaller ratio with respect to one or more other lamps in case the first lamp is in the coded light transmission mode, but with a larger ratio with respect to one of the other lamps transmitting the message in case the first lamp is in the uncoded light transmission mode.

7. A first lamp according to any preceding claim, wherein the communication interface is configured to perform said communication via a constrained signalling channel, whereby propagation of the one or more signals is constrained by physical properties of the luminaire, thereby limiting the one or more signals to be communicated only between those lamps in the same multi-lamp luminaire and not any other luminaires.

8. The first lamp of claim 2, wherein the constrained signaling channel comprises a power supply circuit that powers the first lamp and one or more other lamps, the communication interface being configured to perform said communication by modulating a current and/or voltage of power supplied by said power supply circuit, the propagation of the one or more signals thereby being constrained to the power supply circuit within the same multi-lamp luminaire as the first lamp and the one or more other lamps.

9. The first lamp of claim 7, wherein the constrained signaling channel comprises a power supply circuit that powers the first lamp and one or more other lamps, the communication interface being configured to perform said communication by modulating a current and/or voltage of power supplied by said power supply circuit, the propagation of the one or more signals thereby being constrained to the power supply circuit within the same multi-lamp luminaire as the first lamp and the one or more other lamps.

10. A first lamp as claimed in any one of claims 1 to 6, 8 and 9, wherein the first lamp takes the form of a retrofit LED-based lamp for replacing a fluorescent tube.

11. A multi-lamp luminaire comprising a first lamp according to any preceding claim and one or more further lamps.

12. The multi-lamp luminaire of claim 11 comprising a shared optical cavity in which a first lamp and one or more other lamps are disposed.

13. The multi-lamp luminaire of claim 12, wherein the optical cavity is formed within the diffuser.

14. A method of operating a group of lamps in a multi-lamp luminaire, wherein the group of lamps comprises a first lamp and one or more other lamps in the multi-lamp luminaire, each lamp being operable to emit a respective illumination embedded with a predetermined coded light message, and each lamp comprising a respective local controller;

wherein the method comprises the following steps:

communicating between local controllers of lamps within a multi-lamp luminaire for coordination, such that unsynchronized instances of said coded light message are not transmitted from different ones of the lamps in the multi-lamp luminaire,

the coordination includes any of:

a) coordinating such that each of the first lamp and the one or more other lamps transmits a respective instance of the same coded light message and synchronising all instances of said message to start transmitting at the same time; or

b) Coordinating such that only one lamp among the lamps in the multi-lamp luminaire transmits a message and none of the other lamps among the lamps in the multi-lamp luminaire transmits any coded light, such that if a first lamp is to transmit said message, the local controller selects to operate the first lamp in a coded light transmission mode in which the coded light emitter transmits said message, and if one of the other lamps is to transmit the message, the local controller selects to operate the first lamp in a non-coded light transmission mode in which the first lamp does not transmit said message.

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